Large apertures of telescopes are used for

The ratio of resolving powers of an optical microscope for two wavelengths $\lambda_1 = 4000\,\mathring{A}$ and $\lambda_2 = 6000\,\mathring{A}$ is

Resolving power of a telescope increases when

At Kavalur in India,astronomers using a telescope whose objective had a diameter of $1 \, m$ started using a telescope of diameter $2.54 \, m$. This resulted in:

The diameter of the pupil of the human eye is about $2 \, mm$. The human eye is most sensitive to the wavelength of $555 \, nm$. The limit of resolution of the human eye is ....... $min$.

Two vertical poles are at a distance of $6.28 \, m$ from each other. What should be the maximum distance of an observer from the poles to see them separately? (in $km$)